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Empty vials with vaccines
Photo By: Nathan Denette / ZUMA Press / IMAGO
The good news is that the vaccines available to date against the coronavirus are generally very effective.
With generally minor side effects, they significantly reduce the risk of severe Covid-19 disease and death.
But they could be even better by reliably protecting against future variants of the pathogen.
Or even better: Even from more distant relatives of Sars-CoV-2.
So far this is wishful thinking.
But researchers around the world are working on the development of such optimized vaccines.
Some candidates are already being tested in clinical trials.
The current rampant omicron variant shows that the protective effect of previous preparations such as those from Biontech/Pfizer, Moderna or AstraZeneca can decrease with the constant change in the virus.
Although the available vaccinations still significantly reduce the risk of serious illness and death, they hardly protect against infection with this variant.
The aim of a universal vaccination is therefore to build up an immune response that remains effective even with certain deviations in the virus structure.
All of today's corona vaccines focus on the spike protein, i.e. the spikes on the surface of the virus.
All or part of the protein is presented to the immune system during vaccination so that it can mount antibodies and other cellular immune responses against it.
However, the spike protein in particular is constantly changing.
Future vaccines should therefore target the spike proteins of various known virus variants.
"The hope is that this will trigger the broadest possible immune response and thus also provide protection against future variants," explains Peggy Riese from the Helmholtz Center for Infection Research in Braunschweig.
However, next-generation vaccines could target not just the spike protein, but other, less variable regions of the virus.
Before the end of this year, the US company ImmunityBio wants to launch a second-generation Covid-19 vaccine that builds up an immune reaction against the spike protein and the so-called nucleocapsid.
The nucleocapsid is a protein that is involved in the packaging of the viral genome and is less able to change.
Peter Kremsner considers the second approach to be the theoretically better option.
However, it is still unclear whether the development will succeed.
"The desire for a universal vaccine is certainly justified, but it is not easy to implement," says the director of the Institute for Tropical Medicine at the University of Tübingen.
Means also for cancer patients
Ideally, vaccines that address the conserved – i.e. less changeable – areas of the virus not only protect against different variants of a corona virus, but also against different corona viruses such as the Sars corona virus or the related Mers corona virus.
The research approach is fundamentally correct, believes Peggy Riese.
However, research into the development of universal vaccines is still in its infancy.
A lot of basic information about the virus, its distribution in nature or its interactions with human cells was still missing.
Another problem is that the less variable areas of the virus are often less visible to the immune system and, above all, more difficult to reach for the antibodies.
Universal vaccines should therefore also build up cellular immunity, which is triggered by T cells.
People in particular who have a problem with the formation of antibodies, such as some cancer patients or people with congenital immune defects, could benefit from such a vaccine.
A team led by Juliane Walz at the University Hospital in Tübingen is working on this.
"We looked in the blood of people who had recovered from Covid-19 to see which protein components of the virus were recognized by the T cells," explains Walz.
“We then selected exactly these peptides for our vaccine.” The Tübingen-based vaccine not only activates the T cells against the spike protein, but also against numerous other virus proteins.
A phase 1 clinical study, in which the basic tolerability and effectiveness is tested in healthy people, was successful.
Researchers recently presented the first results after the vaccination of 14 people with immunodeficiency, including twelve patients with leukemia or lymph node cancer, at the annual meeting of the US Cancer Research Society (AACR, American Association for Cancer Research) in New Orleans.
28 days after the vaccination, 13 patients had developed a robust T cell response.
The researchers reported that it was stronger than the T-cell response in immunocompromised people after vaccination with an mRNA vaccine against the spike protein.
A clinical study with more patients with immunodeficiency is currently being prepared.
If further development is successful, which is by no means certain, the preparation should not be used as a vaccine, but as a special activator for the T cells.
It could then not only protect cancer patients or people with congenital immunodeficiency, but all groups of people whose immune system is weakened, such as the elderly or people after a transplant.
dpa/joe
